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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a640ff3ebe8ebcd54587712b3779d571b26acc2e175ca81bbba231d66eabe2ee' 
  AND token = 'k6mmVYct2LJ5XqLKGdIiuXQQO74SP7zBboE0ztWK5Xs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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