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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'dc9b01aca5b754ccfd8ed5f84536268dece2b23fb7210fac45343768acf829e9' 
  AND token = '6xdR47hZsonCPZ3rWSbe6Tcx0vEwaJEvgUaBJwNpqAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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