SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3fbd0f51753921c9a36d8d0deecb4545b2c772d6e4ab0ec18d5bf56ce22eba8' 
  AND token = 'KgW0MisAgiMD93WysxUsBFz598mJn6JDWas5d25fW1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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