SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1993911d0c42d52680fa109368d4ac7dfc3ca503fa97f259d1f2bb5b398a758c' 
  AND token = 'Bmm8tsRghN8Uhdm7eKpoK8FJIxp0wGyTuWiVmAf+/Us=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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