SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5c88adcc92ad886d97eaba02bd295ead0cd19890ff465bd436cb161f097ae55' 
  AND token = '5myRq1Z3DQjVsghNOIdU2dCnv9sY8+BozsQFEbIoKgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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