SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '746b3ce5ce67ba01063a2555c473910f570013d21a3bdf6f00115c56037d5713' 
  AND token = '+053IOyTbR5neIl3a8cBZAWIUOPUzngHSEInizeexIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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