SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5cbe95f550bccbdef0a18d2fdb3820fce46394d569877c86336a961ed39dfc6' 
  AND token = 'oyuNs3SSU3tYs0uMVIWmm5eXcYrVjW5tSLqlk9ZdAlY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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