SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9956417033c8920b0999b0080f69332b6ffcfa09f2229c1360f8581875fc081' 
  AND token = 'd+nFmnFzPo8jagzi1vJQinRuzmWnQZ5+zQvcqTzEx2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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