SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2678472c35947cb9800e8150f5b5c877df7c69502993fe81adab0a459fd3365' 
  AND token = '5d4/McZgNj3xE2DzE7dN0NJbCzcAFGHSc8awccMV0oU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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