SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66b449644d3100db28ede6e46e21f12ccfdb20449d2da36d0c1db4e79f6802f8' 
  AND token = 'WgMfYq9MSCKh7ZfMhKRxfIgUniI5XyU/qF1cEl4YyZk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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