SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '835dcf0537432270e2db51727b0ef1805ed6cda8445bb96faa83df175cd1d131' 
  AND token = 'eIlKAqbJIKcjEmmMuYJaDm1N8XDnVCLehwSm4waJdac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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