SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a9e7683c9d51822fe7f6faf28a1405802b410a589eabeb21cc9d8a9fb136388' 
  AND token = 'PqmbE16udizlYvvENAGMoFOMr5kjzCI03cUfXz3w0T8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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