SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4b3f0b20e7684cd4c3cef80850ceea34aade4a691dc36baf80923a61b3c029c' 
  AND token = '0sGlCjwfWunF0rfDV4kDLs81EwMBLNkBxpJTJLfAT18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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