SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28896f3b8e683ca30155410f68f42eb5bfda39ab8e72c410b0c618fbeea5f6f7' 
  AND token = 'tDEw7UJZClVM5yQ1ygmMN7g38aQRu73Sw5gUq+CQf2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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