SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbff319e244b9b9c99b6f85de22fab31951cfdab35b2244617f9f75305fe6744' 
  AND token = 'xKBlAeAzUWogjFIu22QWKctXmmlBe9d7vcZube9XoKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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