SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db00a154ddb303295337595669a0c0d5a221c521e346f0b915d9e876a0f1f2d1' 
  AND token = 'Q14N4ToIF8DbUqgQpxwDu5AvIH2Q5YnawPdI7sMJHrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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