SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53689d93f3170311addb6c36b4f524d851689f6d99ed78f00ae7ad4b71bc8d74' 
  AND token = '97mMX5CPQHURkyzllVSUb3ZunlQlcnuWbJ7dD2huLCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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