SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd17c6117924cc404443e7e5a19927b046ff220180a5f2be4a5ba3a9174dc062' 
  AND token = 'iLOTMiZul7agfjF3+j/S6jhx3YGwzdc888t4bj75754=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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