SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdc8e88292ede88648eea4deec11b23eb6037d27c02a66837991ce23fae609db' 
  AND token = 'g9MtBONQpRBSk4QCUDUmjirdiB4nqCot1J/PjleEamA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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