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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e55d42d59bd0320cf0e9fea9b48473768327ba56c7b50bae56e65a8d9ec8a728' 
  AND token = 'o9eSzebVqZFi0nwM+5vkRPYFBEUVCYM0N2kmzPpr1Pw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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