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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ff66dc15a0b76104da0e49671d5f18a6d9e8fcabb88db7972ca9e243042fa184' 
  AND token = 'csTTD4qikq6F2aWhq7XvffO189Jbo+DINrE1fQgieYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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