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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a8adfaf6b4efb7e5ee0f3a11be9b74a4b9e7a28a8d712148de231c63a3cba73' 
  AND token = 'npBJfOGd0nWd3bJEiZrpRpVwIDUq5x2sWXgt2H0m2WM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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