SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f90a9d169aee2edf547ed1ae8e7e3036a6e0ab6a188fbfa1d438573e26b984e' 
  AND token = 'bBCtZqG4ltB4Kzu9/5hgXVpYbzSv0qBlw4NcZI0Gh1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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