SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f904076b9719e625c1833531669e9c0e05fb451932f7dcc079dfc4d4e2b2d18' 
  AND token = '40qBUTmX5qdL1KkXd1hpSMWbWYgUMrXj0QqxThgWWf4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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