SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe443c71eea6b86c6a692e0356eb1a9204c4500d510c1dfbe0187d191ebffb50' 
  AND token = '1qozUkBOY19naqKgi+uiR+nCOUOHjGELLfPbrFt2Uf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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