SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be3756cf6393e2c49ec073bb1fa8819d06b267b34402d92e0794262b762ddd66' 
  AND token = 'IU2Vjamfc4/fwGhTsqtWwJuEyYl+ONLz35MQ0I8Pv8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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