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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a66a9179880996684eb6f3f1e4ad649ccfb61e42d7a2b0e7d05b5e0bdd7a7a43' 
  AND token = 'dilnEgbh3tjrBY6kRnUfIERaUTEMYiEqzeBsHjpEjkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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