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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18eb3261cade804d1dd56246b2a378eed15bdc255e578f335875b9df8cdc21a1' 
  AND token = '89Mt4SMchxG4wxmrFlprlAqC4aW3xBW+7J05zlJik7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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