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SELECT 
  1 
FROM 
  tmall_lock_keys 
WHERE 
  key_id = '9e91404b2aed2babe17628f898ea4b3d1d7dec43a4d79621a9394948d7d25a78' 
  AND token = 'U1Qb2a806RzH1rY37gIAfIE4xCHHMjHr7csEUY4+L5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00793

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}