SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f3f117577591f696eee8056b8f1d602ba094d69f68c121780104959ba29ff50' 
  AND token = 'nVIgrgh+uxnQHMELpalFy7hG0/ylOg3drT0tFgqL7ZE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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