SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02d266234d1b70651a043243183cbc120460ccd7124f00acd1d8026b43ff45e2' 
  AND token = 'LBkiDAUTupq6+dV4JJ76dIFlXoNnxUuntIEMdzxMqQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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