SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '017f420f4109a628742c58f979f0963bcf3b813be00384526d209c7f611c0bfc' 
  AND token = 'YmiCmhuWpr6UxPSFO7QMLEWLpJZDYpKK4FhAjaViU/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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