SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd8b0863e68d4d2bde9b330a48d121c8220778560d590fec946121343786d2cc' 
  AND token = 'On2FWWlkdhiqr6k39cj4gh5BJ4MOkHIvQ2ZAnRcKsZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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