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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e297c9df1b14515bbcab9cda8ec6608bd79d8c0fad049f8136f4f1d6a3eb1b9' 
  AND token = 'QcKwSPfHdcj/ADjWd+K9LTtKxH4C4nSVjO5Yy414v3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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