SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a4c6a9430ce193394160394ba0a822377d87ec508e7e4e716efc729fe78ddd5' 
  AND token = 'Kd5QU+/yzvc3gOYvGpqZ2IxBCoG4TgCpE8FZJraU0s4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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