SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a03b7b2114dbadb2d6d3fa936fcd465fdc374d94fe0a3b9d5787653920eec75' 
  AND token = '3d84UY6uU1igEVlbUfkQKCkWDocfI+gSEAOiuld8WLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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