SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '838140e649cc91a479bf168dde0183cf65c40668fd2a973ddf46c35d9d34c9d3' 
  AND token = 'Imhr8wHTvKuqeG7RKxRZL4X5zXUQIcYl0O62iZNKmWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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