SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c63998112fb36f64ac9da7ad3997b2cf208cda5102073161dfe72bc084ff26e5' 
  AND token = '7LAxCXywadEqFJSDPabCVsCmY63V0qEHZw6fjpZKgjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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