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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '12ccce44172294de4d2ac79beed9ad615c067b67de07268f72928c1728a0cfdf' 
  AND token = 'B68/Uxbkfy3Wfpe2cmTgJuZ734fUgDQo16jlgpi1sJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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