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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd4c88eadc2b58e0889743bd090b2ff5b5875a3072c73856824f391e448987bdf' 
  AND token = '+N6U6TqYXt3MOWj0PpfoeJ453WEokC7xSjT4VI3JIRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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