SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a85b34f1438cf338e7314f53fc03b639bdaa67b5f636cfead62ffb51fb842ed' 
  AND token = '7vmjHy996x3UYCi9hTB1/Chd1EBvqVfJKEsu+Py7IRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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