SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '774be2970adc4976638193602281fdde774c3991d623cff5c73623eb07900e89' 
  AND token = 'h9FAKBQNEbwh/pSQZSGj8vRJRvjzt3QyYn0/b+qe9DU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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