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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '752f0d7f3d3cf0479110f650b30bd2ba4563c3d0451ae7ca88eb1eea5808cf15' 
  AND token = 'ZwetTL/RJ+mOe1NQSdDIWcyUAwA7HkYXcVeyHXzTnso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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