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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3eb356ca26cb658d36c99b7d6884f4bcd74378cd198b295f04ec0f4a4a75d00' 
  AND token = 'Wdln9CnZTFgwlaiJ7nYoAFW2dr7jq+Mj/4JC9UEhEUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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