SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0bfe768c8a91fd5f3c688e28a0543a18ace8a854d6f23425079bf430f31f8b61' 
  AND token = '0VLC4xoc+qDRqNNyjnQb+GRAiSm6A1sayL+KJoMV5kQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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