SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '410eac808894db209032484f889d33201d8571e58da894258c01d5b9f2355a07' 
  AND token = 'PUBi7insmdt3YcNHaU7MWvQeQoBFjoj3R+NiQMSYUuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}