SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18358d9c0fcdd734cdeb9f70b415b6f7eb1740e6b81731569dd4747b9ece1d15' 
  AND token = 'B3y9pVrDjHBiwDtsBG/5JNLWXwn+JvYjImsjMd/2qm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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