SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '391efd5d360eb90d853717afaf60d36b62f612e841e56777f3442d2926742821' 
  AND token = 'II31DMqAjD+fEAchYxkeGjIalS2OxsxiTlOQsWc2v0k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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