SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5181391b7c2d7ed19d89a9a2238f9f66eaa9a49188c99c40673655fdf042836c' 
  AND token = 'k8ZNmCR5O33NgUUKaGLXNxjncaOrqFetq8poeVWLIQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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