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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3583d96cf3c9e4ea1fbb9b1c1370d118f04d292ae39b6480d2d6853eb34478d5' 
  AND token = 'f4eBcu36brZDfWEbqP3DGyvRXdATUwwFiTdFzpI+j7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}