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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '36f17e75a3c653cc18fae79dd164ab87f4da1349f59a833594bbb6c7d86d3ef3' 
  AND token = 'OPuG+f+PbsRkL370aMEQDGwpJy3tbHETtBRDgyh628E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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