SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9b2cb5b2878b84df9e12fb6b79d71a90244bd6bd240e77cde7118d6d5c21c34' 
  AND token = 'HfQALwjftgruwWQg29zSfCSKfP5S6WZHRx/Bd94Ac0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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