SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7778fd0e90d359e56a1f65792291d625795b799cd03fa560fe1e79a086549cf6' 
  AND token = 'k8wNeACPE48oKE0nsEicpxp7PqnOgTG8MfY+FlxP8WA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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