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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b476ca78d2d2f86fde5c9412d7b651861ae0cde2369c540d8098d26f3f8e44c3' 
  AND token = 'xjiKPKPVyP0uEita5w/gR3+TNHTjuQbIGwhfkxuXc4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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