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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd2835ea68fb29e8a075524548c847e631bf1cf9d24209e71c8d1d3ea5c769a57' 
  AND token = 'trGJ9D4Mwg6Bia/pnPll0fMqnEyqpbBBGQA7tCuRYk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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