SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1cfe1d7546ac51a782d9e97bf64dbdb70037475298700de91430c647a65fcd83' 
  AND token = 'M2KzpNXud1Nx/4OZrrwnmreVIgIA4kbqpgU42NTsXeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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