SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f8fe2355c6440980bb6ba650f1424b40329c86e763554f6eeab2b6fee3e2d03' 
  AND token = 'ejy7574MCq2py8s9D0Rf43Eo5SdJ//4aestHIPVWprM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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