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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '507a7adeb30d6e3b8c7945f80adbb3e878f0e5fa4cc3778944d36c2abb5a95da' 
  AND token = 'vcdrUPPRzgqcjk8Y7qUxRbmN3kyAnlh62XtsaerMI/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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