SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c39bf757b915ef7d5e72ad97ec19434fe7853896b20e3846d1a111013550373' 
  AND token = 'v/utD9MI/DDYCGj67pU9Cmv8+wpDP6NgdEgrTGFIptE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}