SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4024baf4df972b9315f01cd4a25f5d0c5b3c875a931f02e9aa59b364b9f3fa55' 
  AND token = 'QPRcI/s14g5uzAnZ+dQWYa04ngyU5Ctrf6YUpyonUMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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