SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3d9631c808cc0383081edb42841b43aef9f3db7593874116d53af30a0db3092' 
  AND token = '4svIp7rYBgRgUmjgFtAOxy/QufpfcyAc4WT5GGk2pBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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