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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b834fed84e3835a6cb9098a302ca589ea2e525f6c33206c15cde2b4dd955c78b' 
  AND token = 'RfcDMCGFVNSIu60Y/PyrbpaKock3OBVhlfOMb4CCY08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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