SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fa7d758575ca734682ca84ca4e8ad7b6aeed669a86c80641bf53a60a8c99d53' 
  AND token = 'StOjwvlLZs8XBf7bbmwKIbshDOgPWYC24N+8VmyFQJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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