SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd260db37f6027e6ded31a1de082619c59f5d861ceb1471939dcfbe0518e855d7' 
  AND token = 'drEqEp+74BdsVeYVFTxupyoY4WoXELOoza5gO5wRF10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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