SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '717d41d5e6002fd306c439dc572e267867eb6139c7d293e67932804d6e95b351' 
  AND token = 'fB0OTyFGiJvXsLkbx+kL+AIODutjfjN8yQUntPa6SFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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