SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '751634f605ed9d58177bfa2cdf1d8a23b39f30cd52eba58977bede69cb6376ba' 
  AND token = 'ppAED3kYYiyfn0z7wILFUx2nZaAi4LxKu0JJnLslMlQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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