SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffc680bdd2bea273e2ec536eabb4160553210a9e318fc2fc6766e40fdee4e795' 
  AND token = 'WiiPUjcXgR13+pInWAgMANRxex+Z3gzldoN40nGSo6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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