SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '505712ba40c5788f445f7cc7353c4a679fad69fc0d9df8ddc5cd8e2623b40951' 
  AND token = 'l0wYI1kZGTRGapuP3wF9NtodGaX1kihoQOuM7vxX+go=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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