SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '286bef241ff263c0a73327fe769b0dd346ddd9a1d0c75509ba409364138f67ac' 
  AND token = '9brCDfdSrJPb/KF8BBI9iarfY14CTClzjX49EZZUqV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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