SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9550b625e44304f975d0783b5d317a8846ca0f8755f56d3766f1bb48ea00106' 
  AND token = 'JpQzRSaMqrKlnxgjHIKzZ/+3ZlZS4oWHbjG3BaTiC00=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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