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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b9931ed39f9c8fce5460d86b7b19c7f98dbaf2dd70635087d3f4c710f70bbe0d' 
  AND token = 'QHSfflsBtB8JehgFCca/6R5fwnHFtSgxgxlSSczCgqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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