SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b205640a19c2283f81396e3c9b4a30f9802c6617575a1f47af817920fd8fe32' 
  AND token = '5KhbwvO2weQP6aciR3Uy5RrSixjOEQdbDQ4pAXeHawI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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