SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4c533ce83e24e664f1ed5723a9a13526387166bdcd48cda793772142ceff63e' 
  AND token = 'EtMzw++gyCnErjF2Viah0av52IDi+ur9WDUVq0Hx1Ng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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