SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfb53d7d6fff70b91e60b26b5f5ff3e49c68264e4276d869bf7d4f5ae368a117' 
  AND token = 'L9y9M1C1m/2UKTZY13+DYBXFJkNPKcNaitwju2ZbKp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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