SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c473e7e88a23b5ac99fb509996e3807b276842f2db837e74de8f053370cff25' 
  AND token = 'OmGNv6BUBN/2ZivOPslXPoUEVca2vLjvs38ewWJ+6S4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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