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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e5921d82e929aecc715fe88dd70007e6ff7009db0354ffa89025d9f7bfee8271' 
  AND token = 'jQPPXA3GS9Ig9BzqutbmRHDZeFZ0T546eLtY/Slbyhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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