SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c81b80da62fb3ce7997f9900d368001df581d9e9aa3b1b320a178b4a59b91325' 
  AND token = 'XmOfKY+kv5Aj+BC9WR8RA1/SXRPRsqbh8PjM7rgLYSI=' 
  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"
    }
  }
}