SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86a7159de1861e3ffc68b99528edb1ad5648858a916edd11ba40ee24bdd3dc51' 
  AND token = 'BWG9vAmv3DIhRlg2uXGZSMIoKb/IQFDBHfkUYvpjXmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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