SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38a9c21f45fcb090679aad936258990e4c02ba7906c7d622d337bb69fc9e6b3c' 
  AND token = 'TmllhMQBalw2HMWNaiEVgXuFtH1jVTyteWkmJxs2BZ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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