SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fb80522cc147a04e4e0f595a2901f815981fcd1a51ca7fe8a7fbaf2688a3499' 
  AND token = 'sPJ+v0wJJD791lSbJKOe2rdvkoiBzRipTWjr+vD0iqU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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