SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d87927681117c14da554c0d949904e7f1f51427ae335bee6f55046c8e8ed447' 
  AND token = 'fSw6ZOj6GGWSk+Ay+r1eT5TB+MSeI4Fp+qZvntN/rmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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