SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cbdfc49e385b45338b512907a9e35fbef9a5f601f81912c0e8a2f27de728946' 
  AND token = 'N61mkZFoK3VgO6Tb3QkznoZ47CxBbOIX/R+AV1kzpHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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