SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a68c85619374dae27584847ccdef335be61e5bc11b3eefa67fdf86a624daf574' 
  AND token = 'QO84AfAWAotsK0fZKA360qhVhmhhZ58Emx6fCGAjHKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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