SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ca815563478149a777aceb3fc9b737a4297bef45dd23e472c2da4391413d55f' 
  AND token = '/TvpBXKxdduNvtltYKc1jXMkSVWuvIq3FexSXtAcMr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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