SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5017112bb9ba6e912419f47ce9c7c7e6066b88e269b1b5b3afeb5dac30d6d78b' 
  AND token = 's7hdVexMhuiCoZgGeRUEAwTxTKI2PAtSpcePpKVeREQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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