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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '325680a3fe0001eb89dab6a26e35da46da0255385618935a076808d5e72ca118' 
  AND token = '3+LK67oXXW0fBf1bqCieNHH8DQvRGqW/IM2LalDp4Lg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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