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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4af4d4efc1fba05830a7ebe4f1b00b9c967a4df2651ab22afd5d464383a293e5' 
  AND token = 'zrUxRkOVLI6Wvbuh3RSty0RGp3PsLdvUI6xJ62FUI+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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